Emission lines of Fe XI in the 257--407 A wavelength region observed in solar spectra from EIS/Hinode and SERTS

Theoretical emission-line ratios involving Fe XI transitions in the 257-407 A wavelength range are derived using fully relativistic calculations of radiative rates and electron impact excitation cross sections. These are subsequently compared with both long wavelength channel Extreme-Ultraviolet Imaging Spectrometer (EIS) spectra from the Hinode satellite (covering 245-291 A), and first-order observations (235-449 A) obtained by the Solar Extreme-ultraviolet Research Telescope and Spectrograph (SERTS). The 266.39, 266.60 and 276.36 A lines of Fe XI are detected in two EIS spectra, confirming earlier identifications of these features, and 276.36 A is found to provide an electron density diagnostic when ratioed against the 257.55 A transition. Agreement between theory and observation is found to be generally good for the SERTS data sets, with discrepancies normally being due to known line blends, while the 257.55 A feature is detected for the first time in SERTS spectra. The most useful Fe XI electron density diagnostic is found to be the 308.54/352.67 intensity ratio, which varies by a factor of 8.4 between N_e = 10^8 and 10^11 cm^-3, while showing little temperature sensitivity. However, the 349.04/352.67 ratio potentially provides a superior diagnostic, as it involves lines which are closer in wavelength, and varies by a factor of 14.7 between N_e = 10^8 and 10^11 cm^-3. Unfortunately, the 349.04 A line is relatively weak, and also blended with the second-order Fe X 174.52 A feature, unless the first-order instrument response is enhanced.Comment: 9 pages, 5 figures, 13 tables; MNRAS in pres

Bottom quark mass effects in associated WH production with the H →b b decay through NNLO QCD

We present a computation of next-to-next-to-leading-order (NNLO) QCD corrections to the production of a Higgs boson in association with a W boson at the LHC followed by the decay of the Higgs boson to a bb pair. At variance with previous NNLO QCD studies of the same process, we treat b quarks as massive. An important advantage of working with massive b quarks is that it makes the use of flavor jet algorithms unnecessary and allows us to employ conventional jet algorithms to define b jets. We compare NNLO QCD descriptions of the associated WH(bb) production with massive and massless b quarks and also contrast them with the results provided by parton showers. We find O(5%) differences in fiducial cross sections computed with massless and massive b quarks. We also observe that much larger differences between massless and massive results, as well as between fixed-order and parton-shower results, can arise in selected kinematic distributions

The polarized transition matrix element Agq_{gq}(N) of the variable flavor number scheme at O(αs_{s}3^{3})

We calculate the polarized massive operator matrix element $A_{gq}^{(3)}(N)$ to 3-loop order in Quantum Chromodynamics analytically at general values of the Mellin variable $N$ both in the single- and double-mass case in the Larin scheme. It is a transition function required in the variable flavor number scheme at $O(\alpha_s^3)$. We also present the results in momentum fraction space.Comment: 26 pages Late

The non-first-order-factorizable contributions to the three-loop single-mass operator matrix elements AQg(3)andΔAQg(3)A_{Q_g}^{(3)} \quad \text{and} \quad \Delta A_{Q_g}^{(3)}

The non-first-order-factorizable contributions1 to the unpolarized and polarized massive operator matrix elements to three-loop order $A_{Q_g}^{(3)} \quad \text{and} \quad \Delta A_{Q_g}^{(3)}$ are calculated in the single-mass case. For the $_2$F$_1$-related master integrals of the problem, we use a semi-analytic method based on series expansions and utilize the first-order differential equations for the master integrals which does not need a special basis of the master integrals. Due to the singularity structure of this basis a part of the integrals has to be computed to in the dimensional parameter. The solutions have to be matched at a series of thresholds and pseudo-thresholds in the region of the Bjorken variable $x \in \, ]0, \infty[$ using highly precise series expansions to obtain the imaginary part of the physical amplitude for $x \in \, ]0, 1]$ at a high relative accuracy. We compare the present results both with previous analytic results, the results for fixed Mellin moments, and a prediction in the small-$x$ region. We also derive expansions in the region of small and large values of $x$. With this paper, all three-loop single-mass unpolarized and polarized operator matrix elements are calculated

The three-loop single-mass heavy flavor corrections to deep-inelastic scattering

We report on the status of the calculation of the massive Wilson coefficients and operator matrix elements for deep-inelastic scatterung to three-loop order. We discuss both the unpolarized and the polarized case, for which all the single-mass and nearly all two-mass contributions have been calculated. Numerical results on the structure function $F_2(x,Q^2)$ are presented. In the polarized case, we work in the Larin scheme and refer to parton distribution functions in this scheme. Furthermore, results on the three-loop variable flavor number scheme are presentedComment: 12 page

The three-loop single mass polarized pure singlet operator matrix element

We calculate the massive polarized three-loop pure singlet operator matrix element $A_{Qq}^{(3), \rm PS}$ in the single mass case in the Larin scheme. This operator matrix element contributes to the massive polarized three-loop Wilson coefficient $H_{Qq}^{(3),\rm PS}$ in deep-inelastic scattering and constitutes a three-loop transition matrix element in the variable flavor number scheme. We provide analytic results in Mellin $N$ and in $x$ space and study the behaviour of this operator matrix element in the region of small and large values of the Bjorken variable $x$

The polarized three-loop anomalous dimensions from on-shell massive operator matrix elements

We calculate all contributions ∝TFto the polarized three–loop anomalous dimensions in the M–scheme using massive operator matrix elements and compare to results in the literature. This includes the com-plete anomalous dimensions γ(2),PSqqand γ(2)qg. We also obtain the complete two–loop polarized anomalous dimensions in an independent calculation. While for most of the anomalous dimensions the usual direct computation methods in Mellin N–space can be applied since all recurrences factorize at first order, this is not the case for γ(2)qg. Due to the necessity of deeper expansions of the master integrals in the dimensional parameter ε=D−4, we had to use the method of arbitrary high moments to eliminate elliptic contributions in intermediate steps. 4000 moments were generated to determine this anomalous dimension and 2640 mo-ments turned out to be sufficient. As an aside, we also recalculate the contributions ∝TFto the three–loop QCD β–function

Recent 3-Loop Heavy Flavor Corrections to Deep-Inelastic Scattering

We report on recent progress in calculating the three loop QCD corrections of the heavy flavor contributions in deep--inelastic scattering and the massive operator matrix elements of the variable flavor number scheme. Notably we deal with the operator matrix elements $A_{gg,Q}^{(3)}$ and $A_{Qg}^{(3)}$ and technical steps to their calculation. In particular, a new method to obtain the inverse Mellin transform without computing the corresponding $N$--space expressions is discussed.Comment: Proc RADCOR 2023, 7 pages, 1 figur

A Cellular Potts Model simulating cell migration on and in matrix environments

Cell migration on and through extracellular matrix plays a critical role in a wide variety of physiological and pathological phenomena, and in scaffold-based tissue engineering. Migration is regulated by a number of extracellular matrix- or cell-derived biophysical parameters, such as matrix fiber orientation, gap size, and elasticity, or cell deformation, proteolysis, and adhesion. We here present an extended Cellular Potts Model (CPM) able to qualitatively and quantitatively describe cell migratory phenotype on both two-dimensional substrates and within three-dimensional environments, in a close comparison with experimental evidence. As distinct features of our approach, the cells are represented by compartmentalized discrete objects, differentiated in the nucleus and in the cytosolic region, while the extracellular matrix is composed of a fibrous mesh and of a homogeneous fluid. Our model provides a strong correlation of the directionality of migration with the topological ECM distribution and, further, a biphasic dependence of migration on the matrix density, and in part adhesion, in both two-dimensional and three-dimensional settings. Moreover, we demonstrate that the directional component of cell movement is strongly correlated with the topological distribution of the ECM fibrous network. In the three-dimensional networks, we also investigate the effects of the matrix mechanical microstructure, observing that, at a given distribution of fibers, cell motility has a subtle bimodal relation with the elasticity of the scaffold. Finally, cell locomotion requires deformation of the cell's nucleus and/or cell-derived proteolysis of steric fibrillar obstacles within rather rigid matrices characterized by small pores, not, however, for sufficiently large pores. In conclusion, we here propose a mathematical modeling approach that serves to characterize cell migration as a biological phenomen in health, disease and tissue engineering applications. The research that led to the present paper was partially supported by a grant of the group GNFM of INdA